To preserve the integrity of the corneal epithelium it is essential to maintain a transparent and refractile medium. Persistent epithelial defects and recurrent corneal erosions are painful and may occur if the integrity of the corneal surface is challenged by injury or disease. Epithelial healing becomes compromised when disorders in the adhesion of corneal cells are prevalent. However, there has been no systematic analysis of the initial stage of adhesion when corneal epithelial cells attach and form attachment sites along their basal lamina. The objectives of this proposal are to understand the mechanisms by which basal cells form initial attachment sites on normal and diseased substrates and to examine these interactions that occur between the cell and substrate in vitro and in vivo. Specifically, the aims of the project are: 1) to establish morphological criteria for attachment sites, 2) to identify the proteins and glycoproteins laid down on normal and abnormal substrates in vitro using SDS-PAGE, fluorography and immunoblotting techniques and 3) to examine the attachment of cells in vivo. The adhesion assay developed by the applicant will be used as a vehicle to examine both the attachment of cells and the synthesis of the attachment proteins. By understanding how cells attach and form attachment sites in normal and abnormal corneas, one can potentially develop therapies for those with persistent epithelial defects and recurrent corneal erosions.